If it's the store I work in, we'll be all too happy to help no matter what number you call!
The reason there is a seperate number for customer services now is because when
everyone can get hold of your store's phone number via the website, the phone literally does not stop ringing!
Don't worry about it, if you've got a number use it and whoever's on the other end will try their best to help you!
I feel I should just say though that the Customer Services line gives you to staff that are trained purely to deal with your queries and issues whereas people you speak to at the store may not be so knowledgable! It all depends on what you're calling up for, but don't worry, you won't be "rumbled"! If we can help at all then we will.
CJ